Knee bolster

ABSTRACT

A knee bolster for absorbing the impact to the knees of the occupant during car crash and controlling the posture of the occupant by receiving the knee load securely comprises a pair of left and right panels  1  for receiving the knees and disposed to oppose to the knees, upper stays  2  provided to each of the panels  1  having the rear side of which fixed to the upper area of the corresponding panel  1 , lower stays  3  provided to each of the panels  1  having the lower end of which fixed to the lower area of the corresponding panel  1  and the upper end of which fixed to the front end of the corresponding upper stay  2 , and a connecting member  4  for connecting the pair of deltoid assembled bodies each composed of said panel  1 , said upper stay  2  and said lower stay  3 , the assembled bodies disposed side by side and spaced apart when being connected to the connecting member  4 . The upper and lower stays  2, 3  are arced, and the curvature radius of the lower stays  3  is smaller than that of the upper stays  2.

FIELD OF THE INVENTION

[0001] The present invention relates to a knee protector equipped in a vehicle (hereinafter called a knee bolster) that relieves the impact to the knees of the occupant when a car crash occurs by absorbing the impact energy, and that is capable of securely receiving the load of the knees and thereby controlling the posture of the occupant.

DESCRIPTION OF THE RELATED ART

[0002] A conventional knee bolster is generally composed of two components, a panel 10 for receiving and supporting the knees of the occupant when collision occurs, and a stay 11 that is linearly disposed and that deforms while the panel supports the knees so as to absorb the impact energy (refer to FIG. 6). The front end portion of the stay 11 is fixed to the instrument panel frame 12, and the rear side portion thereof is fixed to the upper area of the panel 10. In order to stabilize the characteristics of the stay 11 by reducing the dispersion of performance based on the differences in the deformation mode caused for example by the various knee height position of the occupant, a deformation starting point 13 such as a groove or notch is provided to the stay so that deformation always starts from the same position. Further, in order to improve resistance, flange surfaces 14 are often provided to both end rims of the stay 11 so as to increase the section modulus thereof.

[0003] In order to effectively absorb impact by the knee bolster, it is necessary to enable the displacement to occur with a fixed deceleration within the range of displacement, or in other words, to maintain a fixed resistance during displacement. However, the stay 11 of the conventional knee bolster does not have an averaged displacement resistance, and the resistance is deteriorated during displacement, so it is difficult to absorb the impact energy with an effective stroke (refer to Table 1) TABLE 1

[0004] There are many reasons why the conventional knee bolster lacks to have a fixed displacement resistance against impact energy and thus cannot effectively absorb the impact energy, and the typical reasons are indicated below. The first problem is that stress is concentrated to one portion of the stay 11 thus deforming only that portion, and when that portion bends the resistance of the whole stay 11 is decreased greatly. The deformation starting point 13 becomes the stress concentration point, and the stay 11 is bent at this point 13 by which the whole resistance of the stay 11 is deteriorated (refer to FIG. 7).

[0005] The second problem is that the flange surface 14 is deformed and opened outward by the deformation of the stay 11 caused by concentrated stress, and the section modulus required to maintain resistance is deteriorated locally. By the deformation of the flange, the stay is even more easily bent, thus the whole resistance of the stay is further reduced (refer to FIG. 8).

[0006] The third problem is that the position of entry of the knees to the panel 10 differs greatly according to the occupant, that is, the knee entry position is high if the occupant is for example a large male, and low if the occupant is a small female. However, the fixture position of the stay 11 is biased toward the upper portion of the panel 10, so if the position of knee entry is low, the lower portion of the panel 10 moves largely toward the upper front direction and rotates around the rear side portion of the stay 11, thus lacking to exhibit resistance, deteriorating the impact absorbing effect of the bolster greatly (refer to FIG. 9). If the knee entry position is high, the impact energy received by the panel 10 can be absorbed by the stay 11 being deformed toward the instrument panel frame 12 (refer to FIG. 7). However, if the knee entry position is low, the stay 11 is often not deformed in the desired manner, and the impact energy cannot be absorbed effectively. When this happens, the panel 10 moves greatly toward the front direction, and the knee bolster cannot exert its function of controlling the posture of the occupant and to absorb the impact energy upon collision.

[0007] If by various reasons mentioned above the knee bolster is undesirably displaced greatly, it may interfere with the sink-in mechanism of the steering column aimed at reducing the possibility of chest injury to the occupant, and this may lead to serious impact to the human body during collision.

SUMMARY OF THE INVENTION

[0008] The present invention aims at providing a knee bolster that solves the problems of the prior art, having a stay that does not give way by concentrated stress to one point, that is capable of maintaining resistance constantly, that can absorb the impact energy in an effective manner, that can suppress the amount of displacement, and that effectively absorbs the impact on and controls the posture of the occupant irrespective of the knee entry position of the occupant.

[0009] In order to achieve the above objects, the knee bolster according to the present invention for reducing the load received by the knees of the occupant during collision comprises a pair of left and right panels opposed to the knees of the occupant for receiving the knees upon collision, an upper stay provided to each panel having the rear side portion of which fixed to the upper area of the panel, and a lower stay provided to each panel having the lower end portion of which fixed to the lower area of each panel and the upper end portion of which fixed to the front end portion of the upper stay, the two substantially deltoid assemblies each constituted of the panel, the upper stay and the lower stay are disposed side to side separated by a predetermined distance, and connected and fixed to a connecting member. According to another example of the invention, the upper stays and the lower stays of the bolster are arced. Even further, according to the present invention, the radius of curvature of the arced lower stays is smaller than the radius of curvature of the upper stays.

[0010] According to the present invention, the knee bolster maintains a constant resistance when displaced within the possible displacement range, and thus can absorb impact energy efficiently. Since the present knee bolster is structured by assembling two upper and lower arched stays together (refer to FIG. 2), upon receiving the load from the knees, the bolster disperses the stress at the arched portion so as not to create a specific stress concentration point to the stays. Thus, the stays are deformed as a whole instead of being bent at one point, and the impact energy can be absorbed efficiently (refer to FIG. 3).

[0011] According to the present invention, the knee bolster maintains a fixed resistance constantly without showing any drop in energy absorption during deformation, and thus can absorb a fixed amount of energy constantly (refer to Table 2). The deformation resistance of the stay is averaged so as to improve the energy absorption performance. TABLE 2

[0012] Moreover, the present knee bolster is capable of providing a stable effect in controlling the posture of the occupant having various build, corresponding to anyone from a typical grownup male to a small female (refer to FIG. 5). Even if the knee entry position is low, the present knee bolster having two (upper and lower) stays absorbs the impact energy effectively, and at the same time, the lower stay supports the load securely, reducing the movement of the panel to the forward direction and thereby controlling the posture of the occupant. The knee bolster exerts its function sufficiently even for occupants of small build. By setting the radius of curvature R₁ of the arced lower stay to be smaller than the radius of curvature R₂ of the arced upper stay, the rear side portion of the lower stay curves back toward the front and extends to the lower area of the panel, being fixed to the panel. The rear side portion of the lower stay extends to the lower area of the panel, so the present knee bolster is capable of exerting a stable resistance against various position and direction of knee entry (refer to FIG. 5).

[0013] As explained above, since the knee bolster is capable of being displaced while maintaining a constant resistance and as a result the amount of displacement is reduced, it rarely interferes with the sink-in mechanism of the steering column. Since it effectively absorbs the impact energy, the present knee bolster provides the same amount of energy absorption with a shorter stroke than the conventional bolster. The remainder space can be utilized as effective space within the instrument panel for disposing other devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a perspective view showing the embodiment of the knee bolster according to the present invention;

[0015]FIG. 2 is a side view showing the embodiment of the knee bolster according to the present invention;

[0016]FIG. 3 is an explanatory view showing the deformation example of the knee bolster according to the present invention;

[0017]FIG. 4 is an explanatory view showing the deformation example when the entry position is low according to the present knee bolster;

[0018]FIG. 5 is an explanatory view showing the corresponding performances according to various positions of entry according to the knee bolster of the present invention;

[0019]FIG. 6 is a side view showing the knee bolster of the prior art;

[0020]FIG. 7 is an explanatory view showing the deformation example of the knee bolster of the prior art;

[0021]FIG. 8 is an explanatory view showing the deformation example of the stay according to the prior art knee bolster; and

[0022]FIG. 9 is an explanatory view showing the deformation example when the entry position is low according to the prior art knee bolster.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] The preferred embodiment of the present invention will now be explained with reference to the accompanied drawings, but the present invention is not limited thereto. In the drawings, reference number 1 denotes the pair of panels (left and right) for receiving the knees of the occupant which are disposed so as to oppose to the position of the knees. Reference number 2 denotes an upper stay disposed to each panel 1, with the rear side portion being fixed to the upper area of the corresponding panel 1. Reference number 3 denotes a lower stay disposed to each panel 1, having the lower end portion being fixed to the lower area of the corresponding panel and the upper end portion being fixed to the front end portion of the corresponding upper stay 2. Two substantially deltoid assembly bodies each constituted of the left or right panel 1, the upper stay 2 and the lower stay 3, are connected and fixed to a connecting member 4 so that they are spaced apart to form a left body and a right body. The upper stays 2 and the lower stays 3 are arced, and the curvature radius of the arced lower stay 3 is smaller than the curvature radius of the arced upper stay 2. By setting the curvature radius R₁ of the arced lower stay 3 to be smaller than the curvature radius R₂ of the arced upper stay 2, the lower end of the lower stay 3 curves back toward the front direction and reaches the lower end of the panel 1 so as to be fixed thereto.

[0024] As explained above, the knee bolster according to the present invention is capable of maintaining a constant resistance while being displaced within the possible range of displacement, thereby effectively absorbing the impact energy caused by collision. When the knee bolster of the present invention receives knee entry, the bolster disperses the stress at the arched portion so as not to create a specific stress concentration point to the stay, thereby preventing the stay from bending at a single point. When the present knee bolster receives knee entry, the stays deform as a whole, absorbing the impact energy efficiently.

[0025] Moreover, the present knee bolster constantly maintains a fixed resistance, and therefore provides a constant energy absorption quantity that does not drop during deformation. Therefore, the present knee bolster provides an improved energy absorption performance by averaging the deformation resistance of the stays.

[0026] Even further, the present knee bolster is capable of effectively and stably controlling the posture of the occupant irrespective of build, for example from a typical grownup male to a small female. Even when the entry position of the knees is low, the present knee bolster having two stays can absorb the impact energy, and since the panel is securely supported by the lower stay, the forward movement of the panel is reduced and the posture of the occupant is stably controlled. The present knee bolster provides sufficient effect even for small build occupants. By setting the curvature radius of the arced lower stay to be smaller than the curvature radius of the arced upper stay, the lower end of the lower stay curves back around facing the front and reaches the lower area of the panel so as to be fixed thereto. Since the front end of the lower stay reaches the lower area of the panel, the present knee bolster exerts stable resistance corresponding to various entry positions and directions.

[0027] Moreover, as explained above, the present knee bolster can maintain a constant resistance while being displaced, thus minimizing the amount of displacement, and as a result, reducing the possibility of interference with the sink-in mechanism of the steering column. Since the present knee bolster absorbs the impact energy efficiently, the same amount of energy absorption can be ensured with a shorter stroke compared to the prior art knee bolster. 

What is claimed is:
 1. A knee bolster for reducing the load acting on the knees of an occupant at the time of collision, said knee bolster comprising: a pair of left and right panels for receiving the knees disposed so as to oppose to the position of the knees; an upper stay provided to each panel, each upper stay having the rear side of which fixed to the upper area of the corresponding panel; a lower stay provided to each panel, each lower stay having the lower end of which fixed to the lower area of the corresponding panel and the upper end of which fixed to the front end of the corresponding upper stay; and a joint member for joining a pair of assembled deltoid bodies each comprising the panel, the upper stay and the lower stay, said assembled bodies being disposed side by side and spaced apart when fixed to the joint member.
 2. A knee bolster according to claim 1, wherein said upper stays and said lower stays are arced.
 3. A knee bolster according to claim 1, wherein said upper stays and said lower stays are arced, and the radius of curvature of the arc of said lower stays is smaller than the radius of curvature of the arc of said upper stays. 